About 80 Eurostar train managers are involved in the dispute.
Photograph: Gareth Fuller/PA

Eurostar rail workers are to go on strike for seven days this month in a dispute over work-life balance – the latest RMT-led row to erupt on the railways this month.

Train managers belonging to the Rail, Maritime and Transport union will walk out from 00.01am on Friday 12 August until 11.59pm on Monday 15 August and for three days over the bank holiday weekend from 27 August.

Eurostar said it would still be able to run most of its timetable, with only one train a day to be cancelled in the first phase of industrial action. It said all passengers who had already booked would be accommodated on alternative trains.

About 80 train managers are involved in the dispute, but many such staff are in French unions and will not be striking; onboard staff will continue to work.

The union said the Eurostar dispute had been caused by the company’s failure to honour a 2008 agreement to ensure that train managers could expect a good work-life balance in terms of unsocial hours and duty rosters.

The RMT general secretary, Mick Cash, said: “Our train manager members at Eurostar have a heavy commitment to shift work and unsocial hours and are sick and tired of the company’s failure to honour agreements.

“Our members have every right to have a fair work-life balance that fulfils the operational needs of the company while guaranteeing quality time off for friends and family. It’s now time for Eurostar to come to the negotiating table with a set of proposals that honours our agreements and guarantees our members a genuine work-life balance.”

A Eurostar spokesman said: “We are aware of the plans for strike action and our focus has been seeking a joint resolution while planning to provide a good service for our customers. On the days of the strike we have made some small changes to our timetable to ensure that all passengers booked to travel will be able to on those days. Passengers affected will be notified in advance.”

Meanwhile, in the Southern row, the RMT union claimed to have had its olive branch rejected by management, as the week of strike action continued with little more disruption than Southern passengers had been experiencing in previous weeks. Cash had offered to suspend strike action set for Thursday and Friday if Southern agreed to urgent talks without pre-conditions.

However, while Govia Thameslink Railway, which operates the Southern franchise, said it was open to talks, bosses intensified their condemnation of the union. The chief executive, Charles Horton, said staff at Southern were “being led astray, and misled repeatedly, by a trade union acting in its own narrow, selfish interests and ignoring the interests of either commuters or their members.

But Cash claimed Southern had “slammed the door” on negotiations, and said the rejection had been dictated by the Department for Transport’s (DfT) rail executive.